Cryo-EM structures of the <i>E. coli</i> replicative DNA polymerase reveal its dynamic interactions with the DNA sliding clamp, exonuclease and <b>τ</b>.

ABSTRACT: The replicative DNA polymerase PolIIIα from Escherichia coli is a uniquely fast and processive enzyme. For its activity it relies on the DNA sliding clamp β, the proofreading exonuclease ε and the C-terminal domain of the clamp loader subunit τ. Due to the dynamic nature of the four-protein complex it has long been refractory to structural characterization. Here we present the 8 Å resolution cryo-electron microscopy structures of DNA-bound and DNA-free states of the PolIII-clamp-exonuclease-τ_c complex. The structures show how the polymerase is tethered to the DNA through multiple contacts with the clamp and exonuclease. A novel contact between the polymerase and clamp is made in the DNA bound state, facilitated by a large movement of the polymerase tail domain and τ_c

SUBMITTER: Fernandez-Leiro R 

PROVIDER: S-EPMC4703070 | biostudies-literature | 2015 Oct

REPOSITORIES: biostudies-literature